Solenoid controlled printing hammer mechanism



United States Patent [72] lnventor Walter l-lladky Chatham, New Jersey [21] Appl. No. 662,043

[22] Filed Aug. 21, 1967 [45] Patented Dec. 1, 1970 [731 Assignees Edward J. Buxton Summit, New Jersey a part interest by mesne assignments; Albert C. Nolte, Jr.

Oyster Bay Cove, New York a part interest by mesne assignments; Walter l-lladky, Chatham, New Jersey a part interest by mesne assignments [54] SOLENOID CONTROLLED PRINTING HAMMER MECHANISM 1 Claim, 4 Drawing Figs.

[52] U.S. Cl 197/49; 101/93; 335/256 [51] Int. Cl B41j 9/24 [50] Field of Search 197/49; 101/93; 335/256 [56] References Cited UNITED STATES PATENTS 2,811,102 10/1957 Devol 101/93 2,843,243 7/1958 Masterson.. 101/93 3,072,045 1/1963 Goin 101/93 3,072,047 1/1963 Maudsley et a]... 101/93 3,217,640 11/1965 Bradshaw 101/93 3,233,540 2/1966 Grottrup 101/93 3,304,858 2/1967 Reach et al.... 101/93 809,796 1/1906 Grabosch 335/256X 2,446,855 8/1948 335/256 2,473,661 6/1949 335/256 2,533,187 12/1950 335/256 Primary ExaminerEdgar S. Burr Attorney- Nolte and Nolte ABSTRACT: A printing mechanism which forms printing impressions on a print medium by a hammer element in conjunction with constantly moving character type. The mechanism includes two solenoids mounted end-to-end and having alined openings therethrough. The hammer element moves entirely under the influences of magnetic fields generated by the solenoids from electric currents supplied and controlled by electronic circuitry.

Patented Dec. 1, 1970 3,543,906

Sheot 2 ot2 /&

INVENTO Q M14752 Hum/(y ATTO NEYS SOLENOID CONTROLLED PRINTING HAMMER MECHANISM The present invention relates generally to a printing hammer control and apparatus, and in particular, to a solenoid controlled printing hammer for use with a rotating drum upon which type characters are placed.

As disclosed in copending U.S. Pat. application Ser. No 484,514 filed Sept. 2, 1965, now abandoned, high speed printers are employed to provide a readout information from a binary coded input. Such printers make use of a rotary drum or wheel, upon which characters, such as letters, numbers, and symbols, are formed along the outer periphery. To produce the printed information, upon a printing medium a printing hammer is caused to strike against an inked ribbon, the printing medium, and the character wheel.

Because of the high speed required in such printers, the control mechanism of the printing hammer must produce a quick response with little or no transients, while still providing a sufficient impact force upon the printing medium to print out a clearly legible character.

Presently known methods of hammer activation and return include the use of a spring which has the disadvantage of producing transients; that is the printing hammer is not returned to the rest position without resulting damped oscillations. Also, the energy expended by the actuating and return spring absorbs some of the striking energy of the hammer, thereby reducing the impact force of the hammer upon the printing medium.

It is, therefore, an object of the present invention to provide in a high speed printer, a high speed printing hammer activator and return means which overcomes the deficiencies of prior art devices.

It is also an object of the present invention to provide a novel solenoid actuated printing hammer for use in a printing mechanism of the type described, in which both the impelling and return forces on the printing hammer are controlled by external electrical signals such as electrical pulses.

A further object of the present invention is to provide in a high speed printer, means for controlling the operation of a printing hammer which requires a minimum of moving parts, thus providing a long and reliable life of the printing equipment.

It is yet a further object of the present invention to provide in a high speed printer, a simple and effective means for operating a printing hammer at high speeds to produce a clear readout in which the movement and impact intensity of the printing hammer is controlled by electromagnetic forces, which are in turn produced by pulse coded electrical signals.

In accordance with the objects of this invention, the printing hammer is made of a ferromagnetic material which is oriented with respect to the central hollow portions of two solenoids, coaxially disposed and in registry with one another. The printing hammer is caused to move in the direction of the printing medium so as to strike against the printing medium through the force created upon the hammer by the electromagnetic field created by one of these solenoids, and is returned to the rest or nonprint position, by the operation of the other solenoid. The timing operation of the solenoids is determined by electrical pulse signals supplied to the solenoids by external electronic control circuitry. Both the impelling force and the return and holding force upon the hammer are produced solely by the forces created by the solenoid fields which act exclusively of one another. That is, only one of the solenoids operates at a given time during the printing sequence.

Further objects and advantages, as well as a more specific description of the invention, may be had from the following specification when studied in conjunction with the enclosed FIGS. in which:

FIG. 1 is a top plan view showing the solenoid control printing hammer as incorporated in a high speed printer, which is shown schematically, showing the relative positions of the printing hammer, with respect to the print medium, ribbon and character wheel;

FIG. 2 is a view of the solenoids and printing hammer taken along line 2-2'of FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2; and

FIGS. 4 a, b, c, and d are schematic diagrams showing the various positions of the printing hammer with respect to the solenoids in a typical print and return operation.

With reference to the FlGS., and in particular FIGS. 1-3, there is shown the inventive hammer control mechanism as employed in a high speed printer of the type described with greater specificity in U.S. Pat. application Ser. No. 484,514 filed Sept. '2, 1965.

In FIG. 1 there is shown in a simplified form, a character wheel 10 upon the'outer periphery of which are disposed characters 11, such as letters of the alphabet, or numbers and symbols, which are to be printed upon a print medium 12, which passes between a ribbon 13 and a printing hammer 14. By the operation of a logic circuit (not shown) which is described in the aforesaid application, the operation of the printing hammer 14 is timed to strike against the print medium when the desired character on the character wheel 10 is disposed directly above the hammer 14, so that the selected character is printed upon the print medium 12 by the striking ofthe hammer 14 against the ribbon 13 and character 11.

As shown in FIGS. land 3, the hammer 14, which is made of a magnetic material such as iron, is disposed within a guide 15, which is substantially of the same cross-sectional shape as the printing hammer 14, and is placed within the passageway of two substantially identical solenoids 16 and 17. Both sole noids are of the type well known in the art and consist mainly of electrical wire wound on a central core. Electrical wires 19 and 20 lead to the external logic circuitry to energize the solenoids 16 and 17 respectively.

As seen in FIGS. 1 and 3, the solenoids 16 and 17 are placed in registry with one another and are mounted along the same longitudinal axis. The hammer 14 is of sufficient length to extend through both of said solenoids when said solenoids are shown in as positioned in FIGS. 1 and 3. In the rest, or nonprinting position, shown in FIGS. 1 and 3, the hammer 14 is held against 'a stop 18 by the force exerted by the return and hold solenoid 17 which is energized with sufficient current to cause the hammer 14 to be magnetically forced against the stop 18. In this position the hammer 14 is so oriented that its transverse central axis is somewhat displaced from the central axis of the impelling solenoid 16 as shown in FIG. 2. The actuation of the printing hammer 14 against the print medium 12 is causedby the energization of the impelling solenoid 16 and the deenergization of return and hold solenoid 17. This is caused by removing the source of current from solenoid 17 and by directing a current to flow through impelling solenoid 16.

The energizing force caused by impelling solenoid 16 causes the hammer 14 to move towards the printing medium 12 and character wheel symbol 11. Under the influence of the constantly applied magnetic field in the impelling solenoid 16, hammer 14 ultimately comes to rest with its transverse central axis in line with the central axis of the impelling solenoid 16. However, a magnetic field of sufficient intensity is provided by the energizing current of solenoid 16, so as to cause the hammer 14 to overshoot the transverse central axis of the solenoid 16 before coming to rest with its central axis coinciding with that of solenoid 16. This overshoot is dependent upon the momentum of the hammer 14, resulting from the intensity of the magnetic field produced by the impelling solenoid 16, and it is this overshoot which is utilized for making the impression upon the printing medium by the hammer striking against the printing medium, ribbon and character simultaneously. The'hammer 14 and impelling solenoid 16 are positioned at a distance from the type face or character on the character wheel 10 so that the hammer 14 will strike the print medium 12 and the ink ribbon 13 to drive them both against the character due to the overshoot produced by the force of impelling solenoid 16. The dwell time of the hammer impact against the character 11 will be dependent upon the distance set between the character 11 and the distance between the hammer 14 at the time of impact and at the stop position. Therefore, the time required for the hammer to return to a stop position determines the amount of dwell time during which the hammer is impacted against the printing medium and character.

FIGS. 4, a, b, c, d, show the various positions of the hammer 14 with respect to the solenoids 16 and 17 in a typical printing operation.

In FIG. 4a the hammer 14 is at rest and is positioned against the stop 18. The impelling solenoid 16 is unenergized while the return and hold solenoid 17 is energized to hold the hammer against the stop. In FIG. 4a, it is clearly seen that the transverse central axis of the hammer 14 is displaced from the transverse central axis of impelling solenoid 16.

In FIG. 4b the hammer 14 is shown in the full overshoot position after being impelled outwardly by the force of the impelling solenoid 16. In this configuration, impelling solenoid 16 is energized, while hold and return solenoid 17 is simultaneously deenergized.

FIG. 40 shows the hammer returning to the rest and hold position with the transverse central axis of the impelling solenoid 16 after having returned from the impact against the print medium. At this time the solenoid 16 is deenergized while solenoid 17 is energized urging the hammer 14 back to the rest position as shown in FIG. 4d which corresponds to the position in FIG. 4a, thus completing a printing cycle. Means (not shown) are provided whereby, after the printer has been inoperative, a signal is first led to solenoid 17, causing the hammer 14 to return to the rest position, so that the hammer 14 is always in the rest position prior to the commencing of the printing operation.

It is within the scope of this invention to vary the impact force of printing hammer 14 upon the printing medium, by varying the amount of electric current energizing the respective solenoids, or by varying the size and disposition of said solenoids with respect to character wheel 10, or with respect to each other.

After a printing operation is performed, the hammer is retained in the rest position by the force exerted by the magnetic field of the return and hold solenoid 17 which turns the hammer back to the rest position and firmly retains it there until the next occasion when 'a printing signal is received by the impelling solenoid 16. I

While I have shown but one embodiment of my invention I desire, however, that my invention be defined by the scope of the claim which is appended below.

lclaim:

1. A printing mechanism having a medium on which printing is placed comprising a plurality of type elements for printing various characters, a movable member on which said type elements are spatially located, said member being movable adjacent to said medium, an elongated printing hammer for striking substantially simultaneously against said medium and a preselected character whereby an imprint is made on said medium, first and second solenoids mounted in end-to-end relationship having alined openings therethrough, said elongated printing hammer being located in said alined openings in both first and second solenoids, a stop adjacent to one end of said printing hammer, means for selectively energizing each of said solenoids, said first solenoid when energized having a magnetic field of sufficient intensity to cause said hammer to overshoot the transverse central axis of said first solenoid and to project beyond the end surface of said first solenoid remote from said second solenoid and to strike against said medium and said selected type element, and said second solenoid when energized withdrawing said hammer away from said element and abutting said stop to a rest position. 

